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Just took her in to start the engine rebuild that's going to add at least 150 HP. he told me I probably need to get rid of the stock 4BBL Rochester and intake. I am thinking I want to go with a Holley 750 CFM. Just starting to do a little research. I don't want to change or cut up the hood and I want to keep the original air cleaner assembly. There is absolutely zero clearance between the air cleaner and the hood right now. Anybody know of the outfit I might need or look into?
 

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The stock intake manifolds flow as good if not better than most of the after market manifolds

about the only gain is weight reduction

Here is a good discussion thread on the topic

http://www.firebirdnation.com/forums/topic/522921-iron-q-jet-intakes-for-pontiac-v8/
I'm not worried about the weight. I'm not building a drag strip car. I am building something to cruise around in and do a few car shows. It would make sense to use a factory intake to make sure there are no clearance problems. I do have an intake off of a 74, 350 in storage. With everything you said about "junk" being added to the newer intakes, do you think the 74 would be better?
 

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and.. What is the right model Holley 750 model? The car currently has electric choke. I am guessing I should stick with that. There's this one on ebay for under $350

http://www.ebay.com/itm/Holley-0-80508SA-750-CFM-Classic-Holley-Carburetor-Electric-Choke-/381411551299?fits=Make%3APontiac%7CSubmodel%3A400&hash=item58cde66843:g:is0AAOSw9r1WAGOf&vxp=mtr

Then there's the double pumper for around $500

http://www.ebay.com/itm/Holley-0-4779S-750-CFM-Double-Pumper-Carburetor-/131609664834?fits=Make%3APontiac%7CSubmodel%3A400&hash=item1ea48c1d42:g:pXIAAOSwWnFWAGNh&vxp=mtr

Is the classic style enough for 400hp?
 

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A 750 Holley wont make any HP diff over a properly done QJ.How does he say your going to gain 150 engine HP without putting a stroker kit in it?I see you have a A/C car so cam selection needs to be taken in to account.After CI HP comes from the heads.You can only do so much with stock heads.Tom
 

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A 750 Holley wont make any HP diff over a properly done QJ.How does he say your going to gain 150 engine HP without putting a stroker kit in it?I see you have a A/C car so cam selection needs to be taken in to account.After CI HP comes from the heads.You can only do so much with stock heads.Tom
Well, I'm not a guru on engine rebuilds. We discussed rebuilding the original heads, performance cam, a lot of machining for other performance internal parts and going to an electric fan. From that, he said I'd be gaining around 150hp. I'm aware that the carb won't increase the HP. Just want to make sure I am getting the right one to keep up with it... I've already gained some with removing the cat converter and adding headers. I am thinking 400 hp total.

If you use the holley on the stock manifold you will need a adapter plate to mount to the spread bore intake.

It will raise the holley 3/4 of an inch

attachicon.gif
SUM-G1401_xl.jpg

http://www.summitracing.com/oh/parts/sum-g1401/overview/
I remember using an adapter plate back in the day. Now to make sure 3/4" is not too much
 

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Dont use a adapter plate,get a stock height intake that will take a holley if your dead set on it.FYI,QJ are run on super stock pontiacs that run in the 9s!People that dont understand them are haters.My RA Vs run holleys and have had them on the dynos with no Xtra HP and way less street gas mileage.Remember that virtually anything you do internally will increase strength and reliability but will show almost no HP increace.Spend your money wisely.Im sure Don will get on here and give you many links for parts.If you stay with iron heads try and keep your CR around 9-9.5.Dont listen to using a bigger cam to bleed off compression.They do it at idle and low RPMs but build compression at higher RPMs,which is the reason we put in larger cams in the first place.Build it right the first time.Tom
 

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Discussion Starter · #9 ·
Dont use a adapter plate,get a stock height intake that will take a holley if your dead set on it.FYI,QJ are run on super stock pontiacs that run in the 9s!People that dont understand them are haters.My RA Vs run holleys and have had them on the dynos with no Xtra HP and way less street gas mileage.Remember that virtually anything you do internally will increase strength and reliability but will show almost no HP increace.Spend your money wisely.Im sure Don will get on here and give you many links for parts.If you stay with iron heads try and keep your CR around 9-9.5.Dont listen to using a bigger cam to bleed off compression.They do it at idle and low RPMs but build compression at higher RPMs,which is the reason we put in larger cams in the first place.Build it right the first time.Tom
I am sure your information is valid. I don't know much about it myself. The guy does build race car engines. There hasn't been a whole lot of communication yet. I will know more as the project progresses, especially when it's time to lay money out for parts. I am just trying to get a feel for myself as to what I need in carburation. Even though I did have the stock carb rebuilt, he did basically tell me that he thought the old Rochester's were junk and that he didn't care much for edelbrocks either... So I'm looking into Holley's
 

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Rochester quadrajets have a following, but i want to say that most people don't like them. From personal experience, they are just as easy to rebuild, but take a special touch to tune them correctly. Diagnosing problems with them is more difficult because they are more complicated. They are more complicated because they regulate fuel alot better between idle, mid range rpm, and high rpm ranges. That is why they get the best of both performance, and street usage. But again, not many people like them, because you can just throw on an edelbrock or holley and without much effort get a running driving car.

The question you have to ask yourself is, do i want to put in the effort to tune it correctly and get the performance and decent MPG? OR do you want an easy to use/tune carburetor that will only get you the performance that you need. Quadrajets were rated at 750cfm, and 800cfm, so with a jet change or two, you CAN get them to flow just as much as the Holley 750's.

If you decide you do want to swap the carb, you need to think about what you want as a replacement. If you really want to keep the stock air cleaner and intake, then you will need to purchase an adapter, or spreadbore carb. Do NOT purchase a Holley spreadbore. You can go with an edelbrock spreadbore, but sounds like your engine builder doesn't like them anyways. The best recommendation i can give you is to purchase an Edelbrock Performer intake, that is stock heighth, and accepts both square AND spread bore. From there, down the road you can swap carb's again.
 

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Discussion Starter · #12 ·
Rochester quadrajets have a following, but i want to say that most people don't like them. From personal experience, they are just as easy to rebuild, but take a special touch to tune them correctly. Diagnosing problems with them is more difficult because they are more complicated. They are more complicated because they regulate fuel alot better between idle, mid range rpm, and high rpm ranges. That is why they get the best of both performance, and street usage. But again, not many people like them, because you can just throw on an edelbrock or holley and without much effort get a running driving car.

The question you have to ask yourself is, do i want to put in the effort to tune it correctly and get the performance and decent MPG? OR do you want an easy to use/tune carburetor that will only get you the performance that you need. Quadrajets were rated at 750cfm, and 800cfm, so with a jet change or two, you CAN get them to flow just as much as the Holley 750's.

If you decide you do want to swap the carb, you need to think about what you want as a replacement. If you really want to keep the stock air cleaner and intake, then you will need to purchase an adapter, or spreadbore carb. Do NOT purchase a Holley spreadbore. You can go with an edelbrock spreadbore, but sounds like your engine builder doesn't like them anyways. The best recommendation i can give you is to purchase an Edelbrock Performer intake, that is stock heighth, and accepts both square AND spread bore. From there, down the road you can swap carb's again.
I appreciate that input. He will put what I want on it and I will discuss more with him about the possibility of an Edelbrock. Honestly, in the beginning I was thinking of going for the full edelbrock package including new heads until I found out the cost. The brief time that we talked about it, he said that Edelbrocks were great Idler's and great at high RPM's, but sucked in between. I don't know a heck of a lot about it, so when someone that builds race cars tells me something, I definitely don't have any room to argue with them, lol.. My Dad use to rebuild engines and he always had Holley's on his cars (and mine when I was young) He's too old to do anything now and probably doesn't even know what an edelbrock is, lol.. I use to be able to ask him about anything and get descent advice. Times have changed
 

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I second this (Do NOT purchase a Holley spreadbore) I have one on my 400 right now and it is terrible it doesn't idle

until it is warmed all the way and then after warmed up all the way it is burning way to rich to the point that it burns my eyes

and no amount of tuning seems to help next chance i get I am picking up a remanufactured Q-jet I used to rebuild them and tune them with no problems
 

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E AFB carbs can be made to work on our pontiacs but do take some work.The performer intake wont flo stock as good as a factory intake.It is hard to find a good aftermarket dual plane square bore intake that is stock height.The E performer RPM is a great intake but is taller.If you want a good pontiac QJ that will be setup properly for you pontiac contact Cliff Ruggles or Sean at SMI.They both build high quality carbs and both drive pontiacs.Tom
 

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I agree with the Q-jet & stock intake. And if that builder don't, I also agree that it may be a good idea to consider another builder. Most guys who think Q-jets are junk, but love Holley's, are Chevy guys, and know VERY little about a Pontiac, or a Q-jet.

I assume your '78 has 6x heads. If you want an iron intake, I'd look for a '72 model. That was the only year that had the small exhaust crossover hole on both sides(so it will work with '72-'79 heads), but didn't have the plumbing for the EGR valve and hot air choke. these items came along in '73.

http://forums.maxperformanceinc.com/forums/showpost.php?p=5522324&postcount=1

http://www.ebay.com/itm/Pontiac-1972-Intake-Manifold-455-CID-/311535565127?hash=item4888f77947:g:ue8AAOSwFqJWqE7C&vxp=mtr

If you fill the blind hole in the passenger side head, with furnace cement, you can run any of the '68-'71 intakes. here's how it's done.

http://www.hotrod.com/how-to/engine/hppp-1301-pontiac-cylinder-head-modification/

Or, if you want a stock height alum intake, you can buy an original or aftermarket RAIV or 455HO alum intake. Most who run these, just run metal block off plates, in place of the stock iron exhaust heat crossover. This is the best way, unless you wanna run a heat crossover, for cold weather driving. If you do want a crossover, you'll have to find one from a '72 455HO. Don't think they make a repro '72 crossover. it was a 1-year only part.

https://www.opgi.com/gto/G240346/

Don't know how much you can spend on a carb. But if you can go $450-$500, I agree on SMI.

https://www.smicarburetor.com/products/sfID1/28/sfID2/9/sfID3/100

If that's a little more than you wanna pay for a carb, Everyday performance can probably build something decent for you.

http://www.everyday-performance.com/quadrajet_carburetors.htm
 

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Discussion Starter · #16 ·
It sounds like the majority are saying I should stay with the factory stuff. It has the factory Qjet and intake on it. One of the first things I did was have the carb rebuilt. It's hard to start when cold, it Idles extra fast and runs like crap until it's warmed up good.. Then it runs OK. The only issue is a dead spot when I romp on it. I don't have the vacuum lines right on it and I know it's not tuned right. I don't think the automatic choke is working right either.

All of those things can be fixed. My issue with staying with the factory setup was thinking I wouldn't have enough fuel delivery for the extra HP. So you guy's think I do? Someone said before that I can change the jets for better performance?
 

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Discussion Starter · #17 ·
So.. I'm gonna talk to him about using a Edelbrock Performer intake with a Holley carb, or keep what's on it and get it right..
 

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"... My issue with staying with the factory setup was thinking I wouldn't have enough fuel delivery for the extra HP. So you guy's think I do ?..."

Yes ! Even stock 750 Q-jets worked well with 455 engines. Your '78 carb, if that's what it is, is an 800cfm. These Q-jets are supporting 10 sec Stockers and 9 sec Super Stockers. Properly set up and tuned, they will provide all the fuel you need. :yes

"...Someone said before that I can change the jets for better performance?"

Changing to bigger jets will only help IF your carb is running lean, on the primaries. And if it's running lean on the secondaries, you must change to metering rods with smaller tips, since the rear jets are not replaceable.

"...The only issue is a dead spot when I romp on it..."

This could be either because the vac pull-off, which is linked to the secondary air flap, is not working properly, or because the spring tension on the air flap is not correct. If the air flap opens too quickly, most street engines just simply can't take the fuel/air mixture dumping that quick, so a bog is the result. And, obviously, if the spring tension is way too tight, there will be a bog, til the flap does finally open. New pull-offs are available, and the flap spring tension is easily adjustable. Chokes are also adjustable.

The stock '73-'79 iron intakes LOOK pretty ugly. And they are heavy. But, it has been proven that they work just as good as the earlier iron intakes and a little better than the Edel Performer. :smile22:
 

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Discussion Starter · #19 ·
"... My issue with staying with the factory setup was thinking I wouldn't have enough fuel delivery for the extra HP. So you guy's think I do ?..."

Yes ! Even stock 750 Q-jets worked well with 455 engines. Your '78 carb, if that's what it is, is an 800cfm. These Q-jets are supporting 10 sec Stockers and 9 sec Super Stockers. Properly set up and tuned, they will provide all the fuel you need. :yes

"...Someone said before that I can change the jets for better performance?"

Changing to bigger jets will only help IF your carb is running lean, on the primaries. And if it's running lean on the secondaries, you must change to metering rods with smaller tips, since the rear jets are not replaceable.

"...The only issue is a dead spot when I romp on it..."

This could be either because the vac pull-off, which is linked to the secondary air flap, is not working properly, or because the spring tension on the air flap is not correct. If the air flap opens too quickly, most street engines just simply can't take the fuel/air mixture dumping that quick, so a bog is the result. And, obviously, if the spring tension is way too tight, there will be a bog, til the flap does finally open. New pull-offs are available, and the flap spring tension is easily adjustable. Chokes are also adjustable.

The stock '73-'79 iron intakes LOOK pretty ugly. And they are heavy. But, it has been proven that they work just as good as the earlier iron intakes and a little better than the Edel Performer. :smile22:
Not the first time you guys have talked me into keeping the stock equipment and saved me a lot of money. It is much appreciated. I'll have him put it back together for me the best he can after the build. He's a pretty smart guy. I doubt he'll have any major issues... If I have to look up a Pontiac expert close by afterwards to get it perfectly in tune, I will.
 

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Discussion Starter · #20 ·
On another note.. Has anyone had any experience with a fast Master injection kit?
 
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